Broad spectrum antibacterial activity of novel bisbenzimidazoles targeting topoisomerase IA and the synergistic composition of bisbenzimidazole with efflux pump inhibitors against pathogenic bacteria

Abstract

The present invention relates to potent antibacterial activity of novel bisbenzimidazoles (SP12a and SP12b) against both Gram positive and Gram negative bacteria and a synergistic composition comprising Bisbenzimidazole (HN12b) in combination with Efflux pump inhibitors against most of the pathogenic bacterial strains.

We claim: 
     
       1. A multi-drug resistant bisbenzimidazole antibacterial agent having bacterial topoisomerase IA inhibitory activity and effective against multi-drug resistant pathogens, the antibacterial agent having the structure: 
       
         
           
           
               
               
           
         
       
       wherein R 1  is 
       
         
           
           
               
               
           
         
       
       and R 2  is 
       
         
           
           
               
               
           
         
       
       wherein the agent is effective against multi-drug resistant pathogens E . coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella planticola, Salmonella typhimurium, Shigella flexineri  and  Mycobacterium tuberculosis . 
     
     
       2. A composition comprising a bisbenzimidazole antibacterial agent and at least one efflux pump inhibitor selected from carbonyl cyanide-m-chlorophenyl hydrazone (CCCP), phenylalanine-arginine-β-naphthylamide (PAβN) or combination of these, wherein the bisbenzimidazole antibacterial agent is selected from the structure: 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are as follows: 
       
         
           
                 
                 
                 
               
                     
                 
                   Compounds 
                   R 1   
                   R 2   
                 
                     
                 
                   SP12a 
                   
                     
                       
                       
                           
                           
                       
                     
                   
                   
                     
                       
                       
                           
                           
                       
                     
                   
                 
                     
                 
                   SP12b 
                   
                     
                       
                       
                           
                           
                       
                     
                   
                   
                     
                       
                       
                           
                           
                       
                     
                   
                 
                     
                 
             
                
                
                
               
               
                
                
                
                
               
            
           
         
       
     
     
       3. The composition of  claim 2 , wherein the bisbenzimidazole antibacterial agent is present at a concentration of 0.25-128 μg/mL and the at least one efflux pump inhibitor is present at a concentration of 0.25-128 μg/mL. 
     
     
       4. An antibiotic composition comprising a bisbenzimidazole antibacterial agent having bacterial topoisomerase IA inhibitory activity and present in an amount of 0.25-128 μg/mL effective to inhibit the growth of Gram positive or Gram negative bacteria and at least one efflux pump inhibitor present in a concentration of 0.25-128 μg/mL and selected from carbonyl cyanide-m-chlorophenyl hydrazone (CCCP), phenylalanine-arginine-β-naphthylamide (PAβN) or combination of these, wherein the bisbenzimidazole antibacterial agent is selected from the structure: 
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  are as follows: 
       
       
         
           
                 
                 
                 
               
                     
                 
                   Compound 
                   R 1   
                   R 2   
                 
                     
                 
                   HN12b 
                   
                     
                       
                       
                           
                           
                       
                     
                   
                   
                     
                       
                       
                           
                           
                       
                     
                   
                 
                     
                 
             
                
                
                
               
               
                
                
               
            
           
         
         wherein the antibacterial agent can selectively inhibit Gram positive or Gram negative bacteria selected from  E. coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumanii, Pseudomonas aeruginosa  and  Klebsiella planticola . 
       
     
     
       5. The antibiotic composition of  claim 4 , wherein the bisbenzimidazole antibacterial agent is HN12b and the efflux pump inhibitors are a combination of CCCP and PAβN. 
     
     
       6. A method of inhibiting Gram positive or Gram negative bacteria, comprising contacting a Gram positive or Gram negative bacteria with an effective amount of the composition of  claim 2  comprising a bisbenzimidazole antibacterial agent and at least one efflux pump inhibitor, wherein the bacteria is a multi-drug resistant pathogen selected from  E. coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella planticola, Salmonella typhimurium, Shigella flexineri  or  Mycobacterium tuberculosis . 
     
     
       7. A method of inhibiting Gram positive or Gram negative bacteria, comprising contacting a Gram positive or Gram negative bacteria with an effective amount of the antibiotic composition of  claim 4  comprising a bisbenzimidazole antibacterial agent and at least one efflux pump inhibitor, wherein the Gram positive or Gram negative bacteria is selected from  E. coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumanii, Pseudomonas aeruginosa  or  Klebsiella planticola . 
     
     
       8. The method of  claim 7 , wherein the bisbenzimidazole antibacterial agent is HN12b and the efflux pump inhibitors are a combination of CCCP and PAβN. 
     
     
       9. The method of  claim 6 , wherein the composition selectively inhibits bacterial topoisomerase IA but does not inhibit Gyrase, Human Topoisomerase I and Human Topoisomerase II at a concentration of 100 μM. 
     
     
       10. The method of  claim 6 , wherein the contacting further results in activation of efflux genes acrAB-ToIC and emrAB-ToIC. 
     
     
       11. The method of  claim 6 , where the contacting further results in down regulation of porins ompC and ompF. 
     
     
       12. A method of inhibiting Gram positive or Gram negative bacteria comprising contacting a Gram positive or Gram negative bacteria with an effective amount of the multi-drug resistant bisbenzimidazole antibacterial agent of  claim 1 , wherein the bacteria is a multi-drug resistant pathogen selected from  E. coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella planticola, Salmonella typhimurium, Shigella flexineri  or  Mycobacterium tuberculosis . 
     
     
       13. The method of  claim 12 , wherein the antibacterial agent selectively inhibits bacterial topoisomerase IA but does not inhibit Gyrase, Human Topoisomerase I and Human Topoisomerase II at a concentration of 100 μM. 
     
     
       14. The composition of  claim 2 , wherein the antibacterial agent and at least one efflux pump inhibitor selectively inhibit bacterial topoisomerase IA in a Gram positive or Gram negative bacteria but does not inhibit Gyrase, Human Topoisomerase I and Human Topoisomerase II at a concentration of 100 μM. 
     
     
       15. The composition of  claim 2 , wherein the antibacterial agent and at least one efflux pump inhibitor selectively inhibit Gram positive or Gram negative bacteria are selected from  E. coli, Enterococcus  sp.,  Staphylococcus  sp.,  Acinetobacter baumanii  and  Mycobacterium tuberculosis . 
     
     
       16. The multi-drug resistant bisbenzimidazole antibacterial agent of  claim 1 , wherein the antibacterial agent has bacterial topoisomerase IA inhibitory activity in a Gram positive or Gram negative bacteria but does not inhibit Gyrase, Human Topoisomerase I and Human Topoisomerase II at a concentration of 100 μM.